Guido Westerwelle, the German foreign minister said on Wednesday that Berlin was prepared to scupper Kiev’s “association agreement” with the EU if Mrs Tymoshenko, Ukraine’s former prime minister, is not allowed adequate medical care. “We Germans say it cannot be ratified if conditions for the rule of law are not also clearly kept to,” he said in a television interview.

The comments came as Austria and Holland announced that government officials and the Dutch royal family would boycott all matches of the Euro 2012 football tournament in Ukraine next month if there was no improvement in Mr’s Tymoshenko’s conditions. Austrian foreign minister Michael Spindelegger said it was “our sign of solidarity” with the politician.

European Commission head José Manuel Barroso has already refused to attend the tournament, and six European presidents will not travel to a summit in Ukraine next week.